Y. Tasinkevych - Academia.edu (original) (raw)
Papers by Y. Tasinkevych
IEEE Signal Processing Letters, 2015
Medical Imaging 2012: Physics of Medical Imaging, 2012
ABSTRACT A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imagin... more ABSTRACT A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity is presented. The property is significant as the element width becomes commensurable with the wavelength of the emitted signal. The angular dependence of the radiation efficiency of the transmit/receive aperture is obtained from exact solution of the corresponding mixed boundary-value problem for periodic baffle system, modeling the transducer array. It is evaluated at the nominal frequency of the excitation signal and is implemented in the developed MSTA algorithm as apodization weights calculated for each imaging point and all combinations of the transmit/receive apertures. The performance of developed method is tested using FIELDII simulated synthetic aperture data of the point reflectors to estimate the visualization depth and lateral resolution. Besides, a FIELDII simulated and measurement data of cyst phantom are used for qualitative assessment of the imaging contrast. Comparison of the results obtained by the modified and conventional MSTA algorithms is given which reveals considerable improvement of the image quality in the area neighboring to the transducer's aperture, and increase of the visualization depth at the cost of slight degradation of lateral resolution near the transducer face.
Acoustical Imaging, 2012
ABSTRACT The paper presents the preliminary results of the computer simulations of the synthetic ... more ABSTRACT The paper presents the preliminary results of the computer simulations of the synthetic aperture method combined with the coded transmission in a linear transducer array. It exploits the transmission of long waveforms characterized by a particular autocorrelation function and allows to increase the total energy of the transmitted signal by its extension, without increasing the peak pressure (limited by safety reasons). It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.
Acoustical Imaging, 2012
ABSTRACT The paper presents modified multi-element synthetic transmit aperture (MSTA) method for ... more ABSTRACT The paper presents modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity, which property becomes significant as the element width becomes commensurable with the wavelength corresponding to the nominal frequency of the transmit signal. The angular dependence of the radiation efficiency of the transmit-receive aperture is approximated by a far-field radiation pattern resulting from the exact solution of the corresponding mixed boundary-value problem for periodic baffle system. The directivity is calculated at the nominal frequency of the excitation signal and is incorporated into the conventional MSTA algorithm. Numerical experiments performed in MATLAB® environment using data simulated by FIELD II program as well as measurement data acquired using the Ultrasonix SonixTOUCH Research system are shown. The comparison of the results obtain by the modified and conventional MSTA methods is given which reveals significant improvement of the image quality, especially in the area neighboring to the transducer's aperture, and increase of the visualization depth at the same time.
Ultrasonics, 2012
The modified synthetic transmit aperture (STA) algorithm is described. The primary goal of this w... more The modified synthetic transmit aperture (STA) algorithm is described. The primary goal of this work was to assess the possibility to improve the image quality achievable using synthetic aperture (SA) approach and to evaluate the performance and the clinical applicability of the modified algorithm using phantoms. The modified algorithm is based on the coherent summation of back-scattered RF echo signals with weights calculated for each point in the image and for all possible combinations of the transmit-receive pairs. The weights are calculated using the angular directivity functions of the transmit-receive elements, which are approximated by a far-field radiation pattern of a narrow strip transducer element vibrating with uniform pressure amplitude over its width. In this way, the algorithm takes into account the finite aperture of each individual element in the imaging transducer array. The performance of the approach developed was tested using FIELD II simulated synthetic aperture data of the point reflectors, which allowed the visualization (penetration) depth and lateral resolution to be estimated. Also, both simulated and measured data of cyst phantom were used for qualitative assessment of the imaging contrast improvement. The experimental data were obtained using 128 elements, 4MHz, linear transducer array of the Ultrasonix research platform. The comparison of the results obtained using the modified and conventional (unweighted) STA algorithms revealed that the modified STA exhibited an increase in the penetration depth accompanied by a minor, yet discernible upon the closer examination, degradation in lateral resolution, mainly in the proximity of the transducer aperture. Overall, however, a considerable (12dB) improvement in the image quality, particularly in the immediate vicinity of the transducer's surface was demonstrated. The modified STA method holds promise to be of clinical importance, especially in the applications where the quality of the "near-field" image, that is the image in the immediate vicinity of the scanhead is of critical importance such as for instance in skin- and breast-examinations.
Archives of Acoustics, 2000
ABSTRACT Synthetic aperture (SA) technique is a novel approach to present day commercial systems ... more ABSTRACT Synthetic aperture (SA) technique is a novel approach to present day commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data. The paper presents the multi-element STA (MSTA) method for medical ultra-sound imaging. The main difference with the STA approach is the use of a few elements in the transmit mode in contrast to a single element aperture. This allows increasing the system frame rate, decreasing the number of emissions, and provides the best compromise between the penetration depth and lateral resolution. Besides, a modified MSTA is proposed with a corresponding RF signal correction in the receive mode, which accounts for the element directivity property. In the experiments a 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of a tissue mimicking phantom obtained using the STA and MSTA methods is presented to demonstrate the benefits of the second one.
Archives of Acoustics, 2000
ABSTRACT The paper presents the theoretical and experimental study of synthetic trans-mit apertur... more ABSTRACT The paper presents the theoretical and experimental study of synthetic trans-mit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
Archives of Acoustics, 2000
The paper presents the optimization problem for the multi-element synthetic transmit aperture met... more The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver performed using the SonixTOUCH Research system are also shown.
IEEE Signal Processing Letters, 2015
Medical Imaging 2012: Physics of Medical Imaging, 2012
ABSTRACT A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imagin... more ABSTRACT A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity is presented. The property is significant as the element width becomes commensurable with the wavelength of the emitted signal. The angular dependence of the radiation efficiency of the transmit/receive aperture is obtained from exact solution of the corresponding mixed boundary-value problem for periodic baffle system, modeling the transducer array. It is evaluated at the nominal frequency of the excitation signal and is implemented in the developed MSTA algorithm as apodization weights calculated for each imaging point and all combinations of the transmit/receive apertures. The performance of developed method is tested using FIELDII simulated synthetic aperture data of the point reflectors to estimate the visualization depth and lateral resolution. Besides, a FIELDII simulated and measurement data of cyst phantom are used for qualitative assessment of the imaging contrast. Comparison of the results obtained by the modified and conventional MSTA algorithms is given which reveals considerable improvement of the image quality in the area neighboring to the transducer's aperture, and increase of the visualization depth at the cost of slight degradation of lateral resolution near the transducer face.
Acoustical Imaging, 2012
ABSTRACT The paper presents the preliminary results of the computer simulations of the synthetic ... more ABSTRACT The paper presents the preliminary results of the computer simulations of the synthetic aperture method combined with the coded transmission in a linear transducer array. It exploits the transmission of long waveforms characterized by a particular autocorrelation function and allows to increase the total energy of the transmitted signal by its extension, without increasing the peak pressure (limited by safety reasons). It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.
Acoustical Imaging, 2012
ABSTRACT The paper presents modified multi-element synthetic transmit aperture (MSTA) method for ... more ABSTRACT The paper presents modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity, which property becomes significant as the element width becomes commensurable with the wavelength corresponding to the nominal frequency of the transmit signal. The angular dependence of the radiation efficiency of the transmit-receive aperture is approximated by a far-field radiation pattern resulting from the exact solution of the corresponding mixed boundary-value problem for periodic baffle system. The directivity is calculated at the nominal frequency of the excitation signal and is incorporated into the conventional MSTA algorithm. Numerical experiments performed in MATLAB® environment using data simulated by FIELD II program as well as measurement data acquired using the Ultrasonix SonixTOUCH Research system are shown. The comparison of the results obtain by the modified and conventional MSTA methods is given which reveals significant improvement of the image quality, especially in the area neighboring to the transducer's aperture, and increase of the visualization depth at the same time.
Ultrasonics, 2012
The modified synthetic transmit aperture (STA) algorithm is described. The primary goal of this w... more The modified synthetic transmit aperture (STA) algorithm is described. The primary goal of this work was to assess the possibility to improve the image quality achievable using synthetic aperture (SA) approach and to evaluate the performance and the clinical applicability of the modified algorithm using phantoms. The modified algorithm is based on the coherent summation of back-scattered RF echo signals with weights calculated for each point in the image and for all possible combinations of the transmit-receive pairs. The weights are calculated using the angular directivity functions of the transmit-receive elements, which are approximated by a far-field radiation pattern of a narrow strip transducer element vibrating with uniform pressure amplitude over its width. In this way, the algorithm takes into account the finite aperture of each individual element in the imaging transducer array. The performance of the approach developed was tested using FIELD II simulated synthetic aperture data of the point reflectors, which allowed the visualization (penetration) depth and lateral resolution to be estimated. Also, both simulated and measured data of cyst phantom were used for qualitative assessment of the imaging contrast improvement. The experimental data were obtained using 128 elements, 4MHz, linear transducer array of the Ultrasonix research platform. The comparison of the results obtained using the modified and conventional (unweighted) STA algorithms revealed that the modified STA exhibited an increase in the penetration depth accompanied by a minor, yet discernible upon the closer examination, degradation in lateral resolution, mainly in the proximity of the transducer aperture. Overall, however, a considerable (12dB) improvement in the image quality, particularly in the immediate vicinity of the transducer's surface was demonstrated. The modified STA method holds promise to be of clinical importance, especially in the applications where the quality of the "near-field" image, that is the image in the immediate vicinity of the scanhead is of critical importance such as for instance in skin- and breast-examinations.
Archives of Acoustics, 2000
ABSTRACT Synthetic aperture (SA) technique is a novel approach to present day commercial systems ... more ABSTRACT Synthetic aperture (SA) technique is a novel approach to present day commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data. The paper presents the multi-element STA (MSTA) method for medical ultra-sound imaging. The main difference with the STA approach is the use of a few elements in the transmit mode in contrast to a single element aperture. This allows increasing the system frame rate, decreasing the number of emissions, and provides the best compromise between the penetration depth and lateral resolution. Besides, a modified MSTA is proposed with a corresponding RF signal correction in the receive mode, which accounts for the element directivity property. In the experiments a 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of a tissue mimicking phantom obtained using the STA and MSTA methods is presented to demonstrate the benefits of the second one.
Archives of Acoustics, 2000
ABSTRACT The paper presents the theoretical and experimental study of synthetic trans-mit apertur... more ABSTRACT The paper presents the theoretical and experimental study of synthetic trans-mit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
Archives of Acoustics, 2000
The paper presents the optimization problem for the multi-element synthetic transmit aperture met... more The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver performed using the SonixTOUCH Research system are also shown.